In addition to having a radio frequency (RF) transceiver, many modern mobile communication platforms also use further front end components such as power amplifiers, active antenna tuners, low noise amplifiers, and antenna switches. Moreover, in multiple antenna systems, such as multiple input multiple output (MIMO) systems, and multiple protocol systems, the RF system may have a multitude of various selectable and configurable components that support each particular signal path and/or protocol. Many of these multiple radio frequency components are controllable by a digital bus in order to provide control and configuration in various operational modes.
One such digital interface bus is based on a standardized protocol developed by the MIPI Alliance called the radio front-end (RFFE) control interface described in the “MIPI® Alliance Specification for RF Front-End Control Interface,” version 1.10-26 Jul. 2011, which is incorporated herein by reference in its entirety. In particular, the MIPI interface is a low complexity interface targeted toward RF systems using semiconductor processes in which logic devices may be potentially costly, and therefore can be implemented in a minimum number of logic gates. The MIPI RFFE control interface bus contains its own power supply voltage, and data is transmitted via a CLK line and a DATA line. Each RFFE slave device coupled to the MIPI RFFE bus is identifiable via a slave identifier, a manufacturer identifier, and a product identifier. A relatively high clock frequency of 26 MHz is used to for the RFFE bus in order to facilitate timing-critical functionality across multiple devices.